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Model comparison

Gemini 3.5 Flash-Lite vs GPT-5.3 Codex

Data verified

Head-to-head evidence from 13 shared benchmark results across 5 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.

N/A
No comparison
66.69/100
0 category wins2 category wins

Public leaderboard positions: Gemini 3.5 Flash-Lite unranked (Not scored); GPT-5.3 Codex #26 (Supported). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.

Evidence parity. Gemini 3.5 Flash-Lite and GPT-5.3 Codex share 13 comparable benchmark results. 2 of 8 categories are comparable. 8 results are unique to Gemini 3.5 Flash-Lite; 8 to GPT-5.3 Codex.

Updated July 21, 2026
Shared results
13
Gemini 3.5 Flash-Lite only
8
GPT-5.3 Codex only
8
Comparable categories
2 / 8

Treat this as a split decision. Gemini 3.5 Flash-Lite makes more sense if you want the cheaper token bill or you need the larger 1M context window; GPT-5.3 Codex is the better fit if coding is the priority.

Confidence note. This is a partial-evidence comparison with 13 shared benchmark results across 5 evidence categories; 2 of 8 categories currently have scoreable aggregates for both models. Treat the verdict as directional until coverage is more balanced.

Why this result

Gemini 3.5 Flash-Lite and GPT-5.3 Codex finish on the same BenchAlign overall score, so this is less about a single winner and more about where the edge shows up. The BenchAlign headline says tie; the benchmark table is where the real choice happens.

GPT-5.3 Codex is also the more expensive model on tokens at $1.75 input / $14.00 output per 1M tokens, versus $0.30 input / $2.50 output per 1M tokens for Gemini 3.5 Flash-Lite. That is roughly 5.6x on output cost alone. Gemini 3.5 Flash-Lite gives you the larger context window at 1M, compared with 400K for GPT-5.3 Codex.

Category breakdown

Exact category averages are shown below. Not measured means BenchLM does not have enough sourced public coverage for that model and category.

Category scores and score margins for Gemini 3.5 Flash-Lite and GPT-5.3 Codex
CategoryGemini 3.5 Flash-LiteΔGPT-5.3 Codex
CodingGemini 3.5 Flash-Lite54.2Margin→ 13.0GPT-5.3 Codex67.2
AgenticGemini 3.5 Flash-Lite63.4Margin→ 8.0GPT-5.3 Codex71.4
ReasoningGemini 3.5 Flash-Lite72.2MarginNo overlapGPT-5.3 CodexNot measured

Decisive benchmark drivers

The largest measured benchmark gaps in this matchup, with exact reported values.

More
A · Gemini 3.5 Flash-LiteB · GPT-5.3 Codex

  1. Terminal-Bench 2.0

    Agentic
    Source ↗
    A 54%B 77.3%
    Winner: GPT-5.3 CodexΔ 23.3
    Terminal-Bench 2.0: Gemini 3.5 Flash-Lite scored 54%; GPT-5.3 Codex scored 77.3%. GPT-5.3 Codex wins this benchmark.

  2. OSWorld-Verified

    Agentic
    Source ↗
    A 74%B 64.7%
    Winner: Gemini 3.5 Flash-LiteΔ 9.3
    OSWorld-Verified: Gemini 3.5 Flash-Lite scored 74%; GPT-5.3 Codex scored 64.7%. Gemini 3.5 Flash-Lite wins this benchmark.

  3. SWE-bench Pro

    Coding
    Source ↗
    A 54.2%B 56.8%
    Winner: GPT-5.3 CodexΔ 2.6
    SWE-bench Pro: Gemini 3.5 Flash-Lite scored 54.2%; GPT-5.3 Codex scored 56.8%. GPT-5.3 Codex wins this benchmark.

Operational comparison

Runtime and commercial metrics are compared only when both models have a complete sourced value.

MetricGemini 3.5 Flash-LiteGPT-5.3 CodexComparison
Input / output priceUSD per 1M tokensGemini 3.5 Flash-Lite$0.3 input / $2.5 outputGPT-5.3 Codex$1.75 input / $14 outputGemini 3.5 Flash-Lite has the lower combined listed price.
Generation speedtokens per secondGemini 3.5 Flash-LiteNot availableGPT-5.3 Codex79 tok/sA complete speed comparison is not available.
First-answer latencyseconds to first tokenGemini 3.5 Flash-LiteNot availableGPT-5.3 Codex88.26 sA complete latency comparison is not available.
Context windowmaximum listed tokensGemini 3.5 Flash-Lite1MGPT-5.3 Codex400KGemini 3.5 Flash-Lite lists the larger context window.

Benchmark Deep Dive

AgenticGPT-5.3 Codex wins
BenchmarkGemini 3.5 Flash-LiteGPT-5.3 CodexResult
Terminal-Bench 2.0Source 54%77.3%GPT-5.3 Codex leads
OSWorld-VerifiedSource 74%64.7%Gemini 3.5 Flash-Lite leads
GDPval-AASource 1140—Not comparable
AA Agentic IndexSource 26.8%—Not comparable
GDPval-AASource 32.0%—Not comparable
AA BriefcaseSource 634—Not comparable
AA Tau3 BankingSource 16.5%—Not comparable
τ²-bench resultsSource —86%Not comparable
Gert LabsSource —57.47%Not comparable
JobBenchSource —33.7%Not comparable
CodingGPT-5.3 Codex wins
BenchmarkGemini 3.5 Flash-LiteGPT-5.3 CodexResult
Terminal-Bench 2.0Source 54.0%—Not comparable
SWE-bench ProSource 54.2%56.8%GPT-5.3 Codex leads
AA Coding IndexSource 49.3%—Not comparable
AA-SciCodeSource 40.9%53.2%GPT-5.3 Codex leads
SWE-bench VerifiedSource —85%Not comparable
SWE-RebenchSource —58.2%Not comparable
Vibe Code BenchSource —61.77%Not comparable
Reasoning
BenchmarkGemini 3.5 Flash-LiteGPT-5.3 CodexResult
MRCRv2Source 72.2%—Not comparable
AA-LCRSource 62.0%74.0%GPT-5.3 Codex leads
CritPtSource 0.0%16.9%GPT-5.3 Codex leads
Knowledge
BenchmarkGemini 3.5 Flash-LiteGPT-5.3 CodexResult
Artificial Analysis Intelligence IndexSource 36.5%44.3%GPT-5.3 Codex leads
AA-GPQA DiamondSource 83.8%91.5%GPT-5.3 Codex leads
AA-HLESource 17.5%39.9%GPT-5.3 Codex leads
AA-Omniscience IndexSource 6.9%9.9%GPT-5.3 Codex leads
AA-Omniscience AccuracySource 30.3%51.8%GPT-5.3 Codex leads
AA-Omniscience Hallucination RateSource 33.5%86.9%Gemini 3.5 Flash-Lite leads
Multimodal
BenchmarkGemini 3.5 Flash-LiteGPT-5.3 CodexResult
AA-MMMU-ProSource 79.0%78.5%Gemini 3.5 Flash-Lite leads
Design Arena WebsiteSource —1193Not comparable
Inst. Following
BenchmarkGemini 3.5 Flash-LiteGPT-5.3 CodexResult
AA-IFBenchSource —75.4%Not comparable
Frequently Asked Questions (3)

Which is better, Gemini 3.5 Flash-Lite or GPT-5.3 Codex?

Gemini 3.5 Flash-Lite and GPT-5.3 Codex are tied on the BenchAlign overall score, so the right pick depends on which category matters most for your use case.

Which is better for coding, Gemini 3.5 Flash-Lite or GPT-5.3 Codex?

GPT-5.3 Codex has the edge for coding in this comparison, averaging 67.2 versus 54.2. Inside this category, AA-SciCode is the benchmark that creates the most daylight between them.

Which is better for agentic tasks, Gemini 3.5 Flash-Lite or GPT-5.3 Codex?

GPT-5.3 Codex has the edge for agentic tasks in this comparison, averaging 71.4 versus 63.4. Inside this category, Terminal-Bench 2.0 is the benchmark that creates the most daylight between them.

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